Method and apparatus for an advanced optical analyzer

ABSTRACT

The present invention provides a sample tank having a window for introduction of electromagnetic energy into the sample tank for analyzing a formation fluid sample down hole or at the surface without disturbing the sample. Near infrared, mid infrared and visible light analysis is performed on the sample to provide a downhole in situ or surface on site analysis of sample properties and contamination level. The onsite analysis comprises determination of gas oil ratio, API gravity and various other parameters which can be estimated by a trained neural network or chemometric equation. A flexural mechanical resonator is also provided to measure fluid density and viscosity from which additional parameters can be estimated by a trained neural network or chemometric equation. The sample tank is pressurized to obviate adverse pressure drop or other effects of diverting a small sample.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims priority from U.S. ProvisionalPatent Application Ser. No. 60/467,668 entitled “A Method and Apparatusfor an Advanced Optical Cylinder” by M. Shammai et al. filed on May 2,2003.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to the field of downholesampling analysis and in particular to a sample tank having a window oran internal light source for introduction of electromagnetic energy intoa confined fluid sample. There response to the introduction ofelectromagnetic energy into the tank is used to perform non-invasiveanalysis of a sample in the tank without opening the tank or otherwisedisturbing the sample.

[0004] 2. Summary of the Related Art

[0005] Earth formation fluids in a hydrocarbon producing well typicallycomprise a mixture of oil, gas, and water. The pressure, temperature andvolume of formation fluids control the phase relation of theseconstituents. In a subsurface formation, high well fluid pressures oftenentrain gas within the oil above the bubble point pressure. When thepressure is reduced, the entrained or dissolved gaseous compoundsseparate from the liquid phase sample. The accurate measurement ofpressure, temperature, and formation fluid composition from a particularwell affects the commercial viability for producing fluids availablefrom the well. The data also provides information regarding proceduresfor maximizing the completion and production of the respectivehydrocarbon reservoir.

[0006] Certain techniques analyze the well fluids downhole in the wellbore. U.S. Pat. No. 6,467,544 to Brown, et al. describes a samplechamber having a slidably disposed piston to define a sample cavity onone side of the piston and a buffer cavity on the other side of thepiston. U.S. Pat. No. 5,361,839 to Griffith et al. (1993) disclosed atransducer for generating an output representative of fluid samplecharacteristics downhole in a wellbore. U.S. Pat. No. 5,329,811 toSchultz et al. (I 994) disclosed an apparatus and method for assessingpressure and volume data for a downhole well fluid sample.

[0007] Other techniques capture a well fluid sample for retrieval to thesurface. U.S. Pat. No. 4,583,595 to Czenichow et al. (1986) disclosed apiston actuated mechanism for capturing a well fluid sample. U.S. Pat.No. 4,721,157 to Berzin (1988) disclosed a shifting valve sleeve forcapturing a well fluid sample in a chamber. U.S. Pat. No. 4,766,955 toPetermann (1988) disclosed a piston engaged with a control valve forcapturing a well fluid sample, and U.S. Pat. No. 4,903,765 to Zunkel(1990) disclosed a time-delayed well fluid sampler. U.S. Pat. No.5,009,100 to Gruber et al. (1991) disclosed a wireline sampler forcollecting a well fluid sample from a selected wellbore depth. U.S. Pat.No. 5,240,072 to Schultz et al. (1993) disclosed a multiple sampleannulus pressure responsive sampler for permitting well fluid samplecollection at different time and depth intervals, and U.S. Pat. No.5,322,120 to Be et al. (1994) disclosed an electrically actuatedhydraulic system for collecting well fluid samples deep in a wellbore.

[0008] Temperatures downhole in a deep wellbore often exceed 300 degreesF. When a hot formation fluid sample is retrieved to the surface at 70degrees F., the resulting drop in temperature causes the formation fluidsample to contract. If the volume of the sample is unchanged, suchcontraction substantially reduces the sample pressure. A pressure dropcauses changes in the situ formation fluid parameters, and can permitphase separation between liquids and gases entrained within theformation fluid sample. Phase separation significantly changes theformation fluid characteristics, and reduces the ability to evaluate theactual properties of the formation fluid.

[0009] To overcome this limitation, various techniques have beendeveloped to maintain pressure of the formation fluid sample. U.S. Pat.No. 5,337,822 to Massie et al. (1994) pressurized a formation fluidsample with a hydraulically driven piston powered by a high-pressuregas. Similarly, U.S. Pat. No. 5,662,166 to Shammai (1997) used apressurized gas to charge the formation fluid sample. U.S. Pat. No.5,303,775 (1994) and U.S. Pat. No. 5,377,755 (1995) to Michaels et al.disclosed a bi-directional, positive displacement pump for increasingthe formation fluid sample pressure above the bubble point so thatsubsequent cooling did not reduce the fluid pressure below the bubblepoint.

[0010] Typically, sample tanks are transported to laboratories foranalysis for determination of formation fluid properties based on thesample. The samples typically have to be transferred to a transportationtank, thus risking sample damage and spoilage due to pressure loss andformation of bubbles or asphaltene precipitation within the sample.Moreover, even if the sample is transferred successfully to thelaboratory, it typically takes weeks or months to receive a fulllaboratory analysis of the sample. Thus there is a need for a rapidsample analysis system that provides accurate results and eliminates therisk of sample spoilage.

SUMMARY OF THE INVENTION

[0011] The present invention addresses the shortcomings of the relatedart described above. The present invention provides a downhole sampletank having at least one window for introduction of visible,near-infrared (NIR), mid-infrared (MIR) and other electromagnetic energyinto the tank for samples collected in the sample tank downhole from anearth boring or well bore. The window is made of sapphire or anothermaterial capable of allowing electromagnetic energy to pass through thewindow. The entire sample tank can be made of sapphire or anothermaterial capable of allowing electromagnetic energy to pass anothermaterial enabling visual inspection or analysis of the sample inside thesample chamber. The present invention also provides interior NIR/MIRlight sources and sensors that communicate from inside of the sampletank via electronic data signals. NIR, MIR and visible light analysis(transmittance, reflectance, and absorption) is performed on the samplevia the window to provide a non-invasive analysis of sample propertiesand contamination level. A single window transmits light reflected off areflective surface inside of the sample tank to obtain transmittancedata through a single window.

[0012] The surface and down hole analysis comprises determination of gasoil ratio, API gravity and various other physical parameters associatedwith the sample which can be calculated or estimated by a trained neuralnetwork or chemometric equation. A flexural mechanical or piezoelectricresonator is also provided to estimate fluid density and viscosity fromwhich additional parameters can be estimated by a trained neuralnetwork, non linear least squares fit, chemometric equation or othersoft modeling techniques well appreciated in the art. The sample tank isover pressurized above the bubble point for the sample to preventadverse pressure drop. When very high pressures are desired the sampleis supercharged with a pressurization gas charge. The down hole sampletank comprises a housing having a hollow interior and at least onewindow, a fiber optics lead, optical conduit or internal light source orsensor for introduction and detection of electromagnetic energy into thesample tank.

BRIEF DESCRIPTION OF THE FIGURES

[0013] For detailed understanding of the present invention, referencesshould be made to the following detailed description of the preferredembodiment, taken in conjunction with the accompanying drawings, inwhich like elements have been given like numerals, wherein:

[0014]FIG. 1 is a schematic earth section illustrating the inventionoperating environment;

[0015]FIG. 2 is a schematic of the invention in operative assembly withcooperatively supporting tools;

[0016]FIG. 3 is a schematic of a representative formation fluidextraction and delivery system;

[0017]FIG. 4 is an illustration of a preferred sample chamber andanalysis top sub;

[0018]FIG. 5 is an illustration of an alternative embodiment having awater pump to pressurize a sample for analysis by an external unit;

[0019]FIG. 6 is an illustration of a common current analysis procedure;

[0020]FIG. 7 is an illustration of the new improved procedure providedby the present invention;

[0021]FIG. 8 is an illustration of an alternative embodiment;

[0022]FIG. 9 is an illustration of an alternative embodiment having aninternal light source and sensor;

[0023]FIG. 10 is an illustration of an alternative embodiment having asingle window and a reflective surface for return of electromagneticradiation;

[0024]FIG. 11 is an illustration of another alternative embodiment usinga Raman spectrometer; and

[0025]FIG. 12 is an illustration of another alternative embodiment usingan external analysis equipment and at least one optical window.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

[0026]FIG. 1 schematically represents a cross-section of earth 10 alongthe length of a wellbore penetration 11. Usually, the wellbore will beat least partially filled with a mixture of liquids including water,drilling fluid, and formation fluids that are indigenous to the earthformations penetrated by the wellbore. Hereinafter, such fluid mixturesare referred to as “wellbore fluids”. The term “formation fluid”hereinafter refers to a specific formation fluid exclusive of anysubstantial mixture or contamination by fluids not naturally present inthe specific formation.

[0027] Suspended within the wellbore 11 at the bottom end of a wireline12 is a formation fluid sampling tool 20. The wireline 12 is oftencarried over a pulley 13 supported by a derrick 14. Wireline deploymentand retrieval is performed by a powered winch carried by a service truck15, for example.

[0028] Pursuant to the present invention, an exemplary embodiment of asampling tool 20 is schematically illustrated by FIG. 2. In the presentexample, the sampling tools comprise a serial assembly of several toolsegments that are joined end-to-end by the threaded sleeves of mutualcompression unions 23. An assembly of tool segments appropriate for thepresent invention may include a hydraulic power unit 21 and a formationfluid extractor 23. Below the extractor 23, a large displacement volumemotor/pump unit 24 is provided for line purging. Below the large volumepump is a similar motor/pump unit 25 having a smaller displacementvolume that is quantitatively monitored as described more expansivelywith respect to FIG. 3. Ordinarily, one or more sample tank magazinesections 26 are assembled below the small volume pump. Each magazinesection 26 may have three or more fluid sample tanks 30.

[0029] The formation fluid extractor 22 comprises an extensible suctionprobe 27 that is opposed by bore wall feet 28. Both, the suction probe27 and the opposing feet 28 are hydraulically extensible to firmlyengage the wellbore walls. Construction and operational details of thefluid extraction tool 22 are more expansively described by U.S. Pat. No.5,303,775, the specification of which is incorporated herewith.

[0030] Turning now to FIG. 4, in an exemplary embodiment of the presentinvention, an advanced optical analyzer (AOA) 800 is provided whichcomprises a sample tank 816 having an integral analytical top sub 818.The sample 821 in the sample tank can be pressurized by the pressurizedcompensation system which comprises a pressure compensation system 810,having a nitrogen pressure chamber 812. The nitrogen pressure isavailable when very high pressure is desired. Pressure is appliedsufficient to keep a down hole fluid sample 821 in chamber 816 above thebubble point pressure and above the pressure at which asphaltenesprecipitate out of the sample. The AOA is also suitable for downholecapture, pressurization and analysis of gas captured in a sample 821confined in chamber 816.

[0031] The present example of the AOA top sub 818 provides one or moreoptical conduits, which in this example are high-pressure sapphirewindows 814 for ingress and egress of electromagnetic energy into theanalysis chamber 800 optical analysis of parameters of interest forformation fluid sample 821. The entire AOA including the analysischamber can be made of sapphire or another material which enableselectromagnetic energy to pass through the material, thereby enablingvisual inspection and noninvasive spectral and other analysis of thecontents of the AOA, including the sample chamber. Optical conduitsother than a sapphire window are acceptable. An analysis module 738comprising a light source, light sensor and processor is provided whichcan be used for analysis of the sample 821 down hole or at the surface.Analysis module 738 is in contact with the sample 821 in sample region823 for transmission and reception of NIR/MIR light into and through thesample in region 823. The light reflected, fluoresced and transmittedNIR/MIR light is analyzed for transmittance, reflectance and luminanceby the processor in analysis module 738. A flexural mechanical resonator840 connected to analysis module 738 by communication line 741 is alsoprovided to determine fluid viscosity, density and other parameters ofinterest for the fluid sample using soft modeling techniques.

[0032] In surface operations, as shown in FIG. 5, the AOA 800 is removedfrom a sample tank carrier and the sample 821 pressure is stabilized bypumping pressurized water 920 behind the piston 921 using pump 910. Atthis time the nitrogen can be released and the nitrogen chamber can bedetached from the sample chamber. An external optical analyzer 930 oranalysis module 738 comprising an NIR/MIR ultraviolet or visible lightsource and spectrometers provided for surfaces or down hole non-invasiveanalysis. The optical analyzer 930 is connected to a NIR/MIR lightsource 832 and a NIR/MIR light sensor 833 for analysis of lighttransmittance, fluorescence and total attenuated reflectance. That is,without disturbing the fluid sample or requiring transferring the sampleto another Department of Transportation (DOT) approved chamber fortransport to an off-site laboratory for analysis.

[0033] The external optical analyzer 930 or internal analyzer 738 in thecurrent example uses wavelength ranges from 1500 nm to 2000 nm to scanthe fluid sample to determine or estimate through soft modelingtechniques, parameters of interest, such as sample contaminationpercentage, gas oil ratio (GOR), density and asphaltene depositionpressure. A tunable diode laser and a Raman spectrometer are alsoprovided in analysis module 738 for spectral analysis of the fluidsample. Each of the light sources and sensors are located inside of thesample tank 816 or communicate with the interior of the sample tank viathe optical window 814 or an equivalent optical conduit providing dataor electromagnetic energy ingress and egress to the interior of thesample tank and the sample retained therein.

[0034] The analysis module 738 is attached as an integral part of thesample tank in the AOA prior to going down hole. The analysis module isused to perform NIR/MIR and other analysis described herein downholeduring a run or at the surface upon completion of a sampling rundownhole. Some of the numerous advantages of the AOA of the presentinvention are shown by comparison to FIG. 6, a prior art system and FIG.7, the new method and apparatus design provided by the AOA of thepresent invention. Note that in FIG. 7 that a primary parametercalculation by optical techniques 1114 is available immediately or inless than six hours and a final PVT report 1132 in less than a week orless rather than six to eight weeks as shown in FIG. 6 for the prior artsystem. An advantage for the disclosed method and apparatus is that nosample transfer is required, as non-invasive surface or down holeequipment in both the analysis module 738 and external equipment 830perform PVT and spectral analysis to determine asphaltene deposition,bubble point, formation volume factor, compositional analysis andadditional analysis described herein.

[0035] Turning now to FIG. 8 an alternative embodiment of the presentinvention is presented showing top sub 818 containing analysis module738 attached to sample chamber 1210 pressurized by nitrogen (N₂) 1212and hydrostatic pressure 1214 while down hole. Thus, the presentinvention can perform sampling and sample analysis while down hole or atthe surface as shown in FIGS. 4, 5 and 8.

[0036] Turning now to FIG. 9, an alternative embodiment is shown whereinan internal light source 830 and an internal sensor 833 are provided fornoninvasive optical analysis of the sample 821. The internal processorembedded in analysis module 738, an external analyzer 930 or a surfaceanalyzer in surface truck 15 process the optical data to determine aparameter of interest for the fluid sample 821. As shown in FIG. 9, todetermine viscosity a ball 1301 is held in place by magnet 1317 andreleased in fluid sample contained in fluid sample chamber 1210. Theball is sensed by magnetic sensor 1319 upon arrival at point 1319. Theprocessor determines the amount of time it takes for ball 1301 to travelbetween point 1317 and point 1319 and determines the fluid viscositytherefrom.

[0037] As shown in FIG. 10, analysis window unit comprises analysismodule 738, tunable diode laser spectrometer 1415 or other opticalspectrometer and sorption cooling unit 1416. Sorption cooling unit 1416is described in co-owned patent application Ser. No. 09/756,764 filed onJan. 8, 2001 entitled Downhole Sorption Cooling in Wireline Logging andMonitoring While Drilling” by Rocco DiFoggio, incorporated herein byreference in its entirety.

[0038] The tunable diode laser 1415 spectrometer enable the ultra highresolution spectroscopy downhole or at the surface. Sorption coolingunit 1416 cools the tunable diode laser as necessary to obviate theadverse affects of downhole temperatures.

[0039] Turning now the FIG. 11, an alternative embodiment of the presentinvention is shown providing an external window unit 1510 for surface ordownhole attachment of analysis equipment such as gas chromatographs orother analysis equipment.

[0040]FIG. 12 is an illustration of an alternative embodiment having asingle optical conduit 814, in this example a sapphire window 814 foringress and egress of electromagnetic energy into and out of the samplechamber 816. Light from light source/sensor 832 enter the sample chamber816 through single optical window 814. The light travels through thesample and bounces off of reflective surface 815. Thus, the round triptransmittance can determined from reflection and return ofelectromagnetic energy. Transmittance is determined for round triptravel of the light through the optical conduit, through the sample,reflected off of the reflective surface, returned through the sample andback through the optical conduit for measurement. Attenuated totalreflectance and fluorescence response data are also sensed but do notuse the reflective surface 815. The data is processed by processor inanalysis module 738, internal analyzer/processor 930 or surfacetruck/controller/processor 15.

[0041] In another embodiment, the method and apparatus of the presentinvention is implemented as a set computer executable of instructions ona computer readable medium, comprising ROM, RAM, CD-ROM, Flash RAM orany other computer readable medium, now known or unknown that whenexecuted cause a computer to implement the functions of the presentinvention.

[0042] While the foregoing disclosure is directed to the preferredembodiments of the invention various modifications will be apparent tothose skilled in the art. It is intended that all variations within thescope of the appended claims be embraced by the foregoing disclosure.Examples of the more important features of the invention have beensummarized rather broadly in order that the detailed description thereofthat follows may be better understood, and in order that thecontributions to the art may be appreciated. There are, of course,additional features of the invention that will be described hereinafterand which will form the subject of the claims appended hereto.

1. An optical analyzer for determining a parameter of interest for aformation fluid sample comprising: an optical analysis chamberassociated with a down hole formation fluid sample; a source ofelectromagnetic radiation associated with the optical analysis chamber;an optical conduit for allowing the electromagnetic radiation inside theoptical analysis chamber for illuminating the fluid sample fornon-invasive analysis of the fluid sample; and an optical analyzerassociated with the optical analysis chamber for analyzing the fluidsample.
 2. The apparatus of claim 1, wherein the optical conduit is asapphire window passing through a wall of the optical analysis chamber.3. The apparatus of claim 1, further comprising: an optical spectrometerfor determining a parameter of interest for the fluid sample.
 4. Theapparatus of claim 1, further comprising: a Raman spectrometer fordetermining a parameter of interest for the fluid sample.
 5. Theapparatus of claim 1, wherein the light source provides light thatpasses through the optical conduit into the sample.
 6. The apparatus ofclaim 1, wherein the optical analyzer receives light that passes throughthe optical conduit.
 7. The apparatus of claim 1, wherein the analysismodule further comprises a piezoelectric resonator for determining aparameter of interest for the fluid sample.
 8. The apparatus of claim 1,further comprising: a soft modeling technique for estimating a secondparameter of interest for the fluid sample from the first parameter ofinterest of the fluid sample.
 9. The apparatus of claim 1, wherein theoptical analysis chamber is made of a material that allows transmissionof electromagnetic energy through the material.
 10. An optical analyzerfor determining a parameter of interest for a formation fluid samplecomprising: an optical analysis chamber associated with a down holeformation fluid sample; a source of electromagnetic radiation inside ofthe optical analysis chamber; an electromagnetic radiation sensor insideof the optical analysis chamber; and an optical analyzer associated withthe optical analysis chamber for analyzing the fluid sample.
 11. Amethod for determining a parameter of interest for a formation fluidsample comprising: retaining a down hole formation fluid sample in anoptical analysis chamber; introducing electromagnetic radiation into theoptical analysis chamber through an optical conduit for illuminating thefluid sample; and analyzing the fluid sample.
 12. The method of claim11, wherein the optical conduit is a sapphire window passing through awall of the optical analysis chamber.
 13. The method of claim 11,further comprising: determining a parameter of interest for the fluidsample using an optical spectrometer.
 14. The method of claim 11,further comprising: determining a parameter of interest for the fluidsample using a Raman spectrometer.
 15. The method of claim 11, whereinthe electromagnetic radiation passes through the optical conduit intothe sample.
 16. The method of claim 11, wherein the optical analyzerreceives light that passes through the optical conduit.
 17. The methodof claim 11, determining a parameter of interest for the fluid sampleusing a mechanical resonator.
 18. The method of claim 11, furthercomprising: estimating a second parameter of interest for the fluidsample from the first parameter of interest of the fluid sample a softmodeling technique.
 19. The method of claim 11, further comprising: achemometric equation for estimating a second parameter of interest forthe fluid sample from the first parameter of interest for the fluidsample.
 20. An method for determining a parameter of interest for aformation fluid sample comprising: retaining a down hole formation fluidsample in an optical analysis chamber associated; generatingelectromagnetic radiation inside of the optical analysis chamber;sensing electromagnetic radiation inside of the optical analysischamber; and an optical analyzer associated with the optical analysischamber for analyzing the fluid sample.
 21. A computer readable mediumcontaining instructions that when executed by a computer perform amethod for determining a parameter of interest for a formation fluidsample comprising: retaining a down hole formation fluid sample in anoptical analysis chamber; introducing electromagnetic radiation into theoptical analysis chamber through an optical conduit for illuminating thefluid sample; and analyzing the fluid sample.
 22. The medium of claim21, wherein the optical conduit is a sapphire window passing through awall of the optical analysis chamber.
 23. The medium of claim 21,further comprising instructions that when executed perform the step:determining a parameter of interest for the fluid sample using anoptical spectrometer.
 24. The medium of claim 21, further comprisingthat when executed perform the step: determining a parameter of interestfor the fluid sample using a Raman spectrometer.
 25. The medium of claim21, wherein the electromagnetic radiation passes through the opticalconduit into the sample.
 26. The medium of claim 21, wherein the opticalanalyzer receives light that passes through the optical conduit.
 27. Themedium of claim 21, further comprising instructions that when executedperform the step: determining a parameter of interest for the fluidsample using a mechanical resonator.
 28. The medium of claim 21, furthercomprising instructions that when executed perform the step: estimatinga second parameter of interest for the fluid sample from the firstparameter of interest of the fluid sample a soft modeling technique. 29.The medium of claim 21, further comprising instructions that whenexecuted perform the step: a chemometric equation for estimating asecond parameter of interest for the fluid sample from the firstparameter of interest for the fluid sample.
 30. A computer readablemedium containing instructions that when executed by a computer performthe a method for determining a parameter of interest for a formationfluid sample comprising: retaining a down hole formation fluid sample inan optical analysis chamber associated; generating electromagneticradiation inside of the optical analysis chamber; sensingelectromagnetic radiation inside of the optical analysis chamber; and anoptical analyzer associated with the optical analysis chamber foranalyzing the fluid sample.
 31. A system for monitoring a parameter ofinterest for a formation fluid sample comprising: a surface processorfor monitoring a down hole tool; an optical analysis chamber associatedwith the tool and associated with a down hole formation fluid sample; asource of electromagnetic radiation associated with the optical analysischamber for allowing electromagnetic radiation inside the opticalanalysis chamber sample for non-invasive analysis of the fluid sample;and an optical analyzer associated with the optical analysis chamber foranalyzing the fluid sample.